BACKGROUND: Osteosarcoma (OS) is one of the most common primary malignant tumors of bone in children, which develops from osteoblasts and typically occurs during the rapid growth phase of the bone. Recently, Super-Enhancers(SEs)have been reported to play a crucial role in osteosarcoma growth and metastasis. Therefore, there is an urgent need to identify specific targeted inhibitors of SEs to assist clinical therapy. This study aimed to elucidate the role of BRD4 inhibitor GNE-987 targeting SEs in OS and preliminarily explore its mechanism.
METHODS: We evaluated changes in osteosarcoma cells following treatment with a BRD4 inhibitor GNE-987. We assessed the anti-tumor effect of GNE-987 in vitro and in vivo by Western blot, CCK8, flow cytometry detection, clone formation, xenograft tumor size measurements, and Ki67 immunohistochemical staining, and combined ChIP-seq with RNA-seq techniques to find its anti-tumor mechanism.
RESULTS: In this study, we found that extremely low concentrations of GNE-987(2-10 nM) significantly reduced the proliferation and survival of OS cells by degrading BRD4. In addition, we found that GNE-987 markedly induced cell cycle arrest and apoptosis in OS cells. Further study indicated that VHL was critical for GNE-987 to exert its antitumor effect in OS cells. Consistent with in vitro results, GNE-987 administration significantly reduced tumor size in xenograft models with minimal toxicity, and partially degraded the BRD4 protein. KRT80 was identified through analysis of the RNA-seq and ChIP-seq data. U2OS HiC analysis suggested a higher frequency of chromatin interactions near the KRT80 binding site. The enrichment of H3K27ac modification at KRT80 was significantly reduced after GNE-987 treatment. KRT80 was identified as playing an important role in OS occurrence and development.
CONCLUSIONS: This research revealed that GNE-987 selectively degraded BRD4 and disrupted the transcriptional regulation of oncogenes in OS. GNE-987 has the potential to affect KRT80 against OS.

BACKGROUND: According to the 2022 Global Cancer Statistics, lung cancer is the leading cause of cancer-related mortality worldwide. Lung adenocarcinoma (LUAD), which is a histological subtype of Non- Small Cell Lung Cancer (NSCLC), accounts for 40% of primary lung cancer. Therefore, there is an urgent need to identify new prognostic markers as clinical predictive markers for LUAD.
OBJECTIVE: This study aimed to investigate the role of Keratin 80 (KRT80) in the prognosis of LUAD and its underlying mechanisms.
METHODS: Bioinformatics analysis was conducted using data retrieved from The Cancer Genome Atlas (TCGA) databases. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were employed to predict the involved biological processes and signaling pathways, respectively. The LinkedOmics database was utilized to identify differentially expressed genes (DEGs) correlated with KRT80. Nomograms and Kaplan-Meier plots were constructed to evaluate the survival outcomes of patients diagnosed with LUAD. Moreover, TIMER was employed to conduct correlation analyses between KRT80 expression and immune cell infiltration, shedding light on the intricate interplay between KRT80 and the tumor microenvironment in LUAD. To ascertain the RNA and protein expression levels of KRT80 in LUAD and adjacent normal tissues, Reverse Transcription-quantitative Polymerase Chain Reaction (RT-qPCR) and immunohistochemistry techniques were employed, respectively.
RESULTS: Scrutiny of the TCGA dataset revealed KRT80 up-regulation across pan-cancer tissues, notably elevated in LUAD compared to healthy lung tissues. This finding was validated in our clinical samples, where Kaplan-Meier survival curves indicated poorer survival rates for high KRT80 expression in LUAD. A positive correlation was found between the transcription level of KRT80 in LUAD samples and clinical parameters, such as lymph node metastasis stage, distant metastasis, and pathological stage. Survival, logistic regression, and Cox regression analyses emphasized the clinical prognostic significance of high KRT80 expression in LUAD. Nomogram results underscored the robust predictive potential of KRT80 for the survival of LUAD patients. Gene functional enrichment analyses mainly associated KRT80 with cytokine-cytokine receptor interactions, cell cycle, apoptosis, and chemokine signaling pathways. Based on the results of the immune infiltration analysis, it can be found that the expression of KRT80 is related to the immune cell subsets and survival rate of patients with LUAD.
CONCLUSIONS: Our research revealed a significant upregulation of KRT80 in LUAD, with heightened KRT80 expression correlating with unfavorable prognosis. This study represents a comprehensive and systematic evaluation of KRT80 expression in LUAD, encompassing its prognostic and diagnostic significance, as well as underlying mechanisms. Our findings suggest that KRT80 may emerge as a novel prognostic and predictive biomarker in LUAD.

Background: Keratin 80(KRT80) encodes a type II intermediate filament protein, known for maintaining cell integrity of cells and its involvement in the tumorigenesis and progression of various cancers. However, comprehensive research on its relevance to lung adenocarcinoma remains limited. Methods: In this study, we utilized multiple databases to investigate the transcriptional expression of KRT80 and its correlation with clinicopathological features. A range of assays, including the Cell Counting Kit 8 assay, colony formation assay, cell migration assay, and flow cytometry, were employed to elucidate the impact of KRT80 on the malignant behavior of lung adenocarcinoma. Immunoprecipitation and mass spectrometry were also used to identify putative genes interacting with KRT80. Results: The expression of KRT80 was elevated in lung adenocarcinoma and patients with high levels of KRT80 expression had poor clinical outcomes. Silencing KRT80 suppressed cell viability, and migration, while overexpression had the opposite effect. In addition, Immunoprecipitation and mass spectrometry revealed an interaction between KRT80 and valosin-containing protein (VCP), with VCP knockdown reducing the stability of KRT80 protein. Overexpression of KRT80 mitigated the inhibitory effect of VCP knockdown to some extent. Conclusion: Our findings collectively suggest that KRT80 is a promising diagnostic and prognostic indicator for lung adenocarcinoma. Additionally, the interaction between KRT80 and VCP plays a crucial role in the progression of lung adenocarcinoma, which implies that KRT80 is a promising therapeutic target.

Keratin 80 (KRT80) is a filament protein that makes up one of the major structural fibers of epithelial cells, and involved in cell differentiation and epithelial barrier integrity. Here, KRT80 mRNA expression was found to be higher in esophageal cancer than normal epithelium by RT-PCR and bioinformatics analysis (p < .05), opposite to KRT80 methylation (p < .05). There was a negative relationship between promoter methylation and expression level of KRT80 gene in esophageal cancer (p < .05). KRT80 mRNA expression was positively correlated with the differentiation, infiltration of immune cells, and poor prognosis of esophageal cancer (p < .05). KRT80 mRNA expression was positively linked to no infiltration of immune cells, the short survival time of esophageal cancers (p < .05). The differential genes of KRT80 mRNA were involved in fat digestion and metabolism, peptidase inhibitor, and intermediate filament, desosome, keratinocyte differentiation, epidermis development, keratinization, ECM regulator, complement cascade, metabolism of vitamins and co-factor (p < .05). KRT-80-related genes were classified into endocytosis, cell adhesion molecule binding, cadherin binding, cell-cell junction, cell leading edge, epidermal cell differentiation and development, T cell differentiation and receptor complex, plasma membrane receptor complex, external side of plasma membrane, metabolism of amino acids and catabolism of small molecules, and so forth (p < .05). KRT80 knockdown suppressed anti-apoptosis, anti-pyroptosis, migration, invasion, chemoresistance, and lipogenesis in esophageal cancer cells (p < .05), while ACC1 and ACLY overexpression reversed the inhibitory effects of KRT80 on lipogenesis and chemoresistance. These findings indicated that up-regulated expression of KRT80 might be involved in esophageal carcinogenesis and subsequent progression, aggravate aggressive phenotypes, and induced chemoresistance by lipid droplet assembly and ACC1- and ACLY-mediated lipogenesis.

KRT80 is a human epithelial intermediate filament type II gene; its expression product is a component of intracellular intermediate filaments (IFs) and is involved in the assembly of the cytoskeleton. There is evidence that IFs form a dense network mainly in the perinuclear area, but they can also reach the cortex. They are essential for mechanical cushioning of cells, organelle positioning, cell apoptosis, migration, adhesion, and interactions with other cytoskeletal components. Humans possess 54 functional keratin genes, and KRT80 is one of the more unique genes. It is widely expressed in almost all epithelial cells, although it is structurally more similar to type II hair keratins than to type II epithelial keratins.
In this review, we summarize the basic facts about the keratin family and KRT80, the essential role of KRT80 in neoplasms, and its potential as a therapeutic target. We hope that this review will inspire researchers to at least partially focus on this area.
In many neoplastic diseases, the high expression status of KRT80 and its role in regulating the biological functions of cancer cells have been well established. KRT80 can effectively enhance the proliferation, invasiveness and migration of cancer cells. However, the effects of KRT80 on prognosis and clinically relevant indices in patients with various cancers have not been extensively studied, and even opposite conclusions have been reached in different studies of the same cancer. Based on this, we should add more clinically relevant studies to clarify the prospect of clinical application of KRT80. Many researchers have made great progress in studying the mechanism of action of KRT80. However, their studies should be extended to more cancers to find common regulators and signaling pathways of KRT80 in different cancers. KRT80 may have far-reaching effects on the human body, and this marker may play a crucial role in the function of cancer cells and the prognosis of cancer patients, so it has a promising future in the field of neoplasms.
In neoplastic diseases, KRT80 is overexpressed in many cancers and plays an essential role in promoting proliferation, migration, invasiveness and poor prognosis. The mechanisms of KRT80 functions in cancer have been partially elucidated, suggesting that KRT80 is a potentially useful cancer therapeutic target. However, more systematic, in-depth and comprehensive studies are still needed in this field.

We recently determined the RNA sequencing-based microRNA (miRNA) expression signature of colorectal cancer (CRC). Analysis of the signature showed that the expression of both strands of pre-miR-139 (miR-139-5p, the guide strand, and miR-139-3p, the passenger strand) was significantly reduced in CRC tissues. Transient transfection assays revealed that expression of miR-139-3p blocked cancer cell malignant transformation (e.g., cell proliferation, migration, and invasion). Notably, expression of miR-139-3p markedly blocked RAC-alpha serine/threonine-protein kinase (AKT) phosphorylation in CRC cells. A combination of in silico database and gene expression analyses of miR-139-3p-transfected cells revealed 29 putative targets regulated by miR-139-3p in CRC cells. RNA immunoprecipitation analysis using an Argonaute2 (AGO2) antibody revealed that KRT80 was efficiently incorporated into the RNA-induced silencing complex. Aberrant expression of Keratin 80 (KRT80) was detected in CRC clinical specimens by immunostaining. A knockdown assay using small interfering RNA (siRNA) targeting KRT80 showed that reducing KRT80 expression suppressed the malignant transformation (cancer cell migration and invasion) of CRC cells. Importantly, inhibiting KRT80 expression reduced AKT phosphorylation in CRC cells. Moreover, hexokinase-2 (HK2) expression was reduced in cells transfected with the KRT80 siRNAs or miR-139-3p. The involvement of miRNA passenger strands (e.g., miR-139-3p) in CRC cells is a new concept in miRNA studies. Our tumor-suppressive miRNA-based approach helps elucidate the molecular pathogenesis of CRC.

Gastric cancer (GC) affects a large proportion of cancer patients worldwide, and the prediction of potential biomarkers can greatly improve its diagnosis and treatment. Here, miR-4268 and keratin 80 (KRT80) expression in GC tissues and cell lines was determined. The effect of downregulating miR-4268 and interfering with KRT80 expression on the viability, proliferation, apoptosis, and migration of GC cells were evaluated. The interaction between miR-4268 and KRT80 was studied using luciferase reporter and RNA pull-down assays. The western blot, CCK-8, BrdU, caspase-3 activity, Transwell assays were performed for the functional characterization. In GC tissues and cells, KRT80 expression was found to be significantly higher, while that of miR-4268 was significantly lower than the respective expressions in normal tissues and cells. Interference with KRT80 expression inhibited the viability, proliferation, and migration of GC cells and facilitated cell apoptosis in vitro. We further demonstrated that miR-4268 targeted KRT80 and negatively regulated its expression, and miR-4268 inhibitor alleviated the inhibitory effects of KRT80 downregulation on GC cell growth. Finally, miR-4268 may function as tumor suppressor through inhibiting PI3K/AKT/JNK pathways by targeting KRT80 in GC. Collectively, our present results indicate that the miR-4268/KRT80 axis acts as a potential therapeutic target for patients with GC.Abbreviations: Gastric cancer (GC); MicroRNAs (miRNAs); Keratin 80 (KRT80); differentially expressed genes (DEGs); chemoradiotherapy (CRT); negative nonsense sequence (NC); radioimmunoprecipitation assay (RIPA); polyvinylidene fluoride (PVDF).

Introduction: Keratin 80 (KRT80) is a type II epithelial keratin protein that plays an important role in cell differentiation and tumor progression. However, its role and mechanisms in ovarian cancer remain unclear. Methods: The effect of KRT80 on the survival and prognosis of patients with ovarian cancer was determined using immunohistochemistry. Cell lines overexpressing KRT80 and with KRT80 knockdown were established to study its effect on the malignant behavior of ovarian cancer cells. Western blotting was used to detect changes in related molecules, and in the MEK/ERK signal transduction pathway. ChIP assay was used to confirm that ETS1 regulates KRT80 at the transcriptional level. A double luciferase assay was used to confirm the target of miR-206. Results: The expression levels of KRT80 were high in ovarian cancer tissue, and were related to survival and prognosis. KRT80 expression is an independent prognostic factor in patients with ovarian cancer. KRT80 overexpression promotes the proliferation of ovarian cancer cells, the transition from G1 phase to S phase, invasion, and migration. KRT80 overexpression increased the expression of BCL2/BAX, CyclinD1, MMP2, MMP9, and N-cadherin, decreased the expression of E-cadherin, and increased the phosphorylation of MEK and ERK. ETS1 binds to the upstream promoter sequence of KRT80 and regulates KRT80 expression at the transcriptional level. ETS1 is a direct target of miR-206 in ovarian cancer cells. Conclusion: KRT80 regulated by miR-206/ETS1 promotes tumor progression via the MEK/ERK pathway in ovarian cancer, and KRT80 may have applications as a screening biomarker and potential therapeutic target for ovarian cancer.

BACKGROUND: Gastric cancer (GC) has been regarded as a kind of the most common cancers in gastrointestinal malignant tumors. Circular RNA (circRNA) is a newly discovered category of non-coding RNAs and plays a significant role in the initiation or development of human cancers. Nevertheless, the role of circPIP5K1A in GC remains unclear.
METHODS: The relative expression level and the circular structure of circPIP5K1A were confirmedby RT-qPCR. The biological function of circPIP5K1A in GC was evaluated by colony formation, transwell and western blot assays. The binding capacity between miR-671-5p and circPIP5K1A (or KRT80) was assessed by luciferase reporter and Ago2-RIP assays. Protein levels of PI3K/AKT pathway were measured by western blot assay.
RESULTS: CircPIP5K1A was up-regulated in GC tissues and cells with a circular structure. Functionally, circPIP5K1A silence limited cell proliferation, invasion, migration and EMT process. Mechanistically, circPIP5K1A directly interacted with miR-671-5p to modulate KRT80 expression. Either miR-671-5p inhibitor or KRT80 overexpression could offset the inhibitory effect of circPIP5K1A depletion on GC development. Besides, circPIP5K1A played its oncogenic role in GC through regulating PI3K/AKT pathway. At last, circPIP5K1A promoted GC tumor growth in vivo.
CONCLUSIONS: CircPIP5K1A/miR-671-5p/KRT80 axis contributes to GC progression through PI3K/AKT pathway, implying this axis may be a potential therapeutic target for the treatment of GC patients.

To elucidate the Cdk5 regulatory molecular mechanism in skin, we generated Cdk5-knockdown mice and subjected their skins to lncRNA sequencing. The results showed that there were 4533 novel lncRNAs from 142 lncRNA families. In total, 693 lncRNAs were significantly differentially expressed. Alignment analysis of the lncRNAs in miRBase identified 45 pre-mRNAs. By KEGG PATHWAY Database analysis, we found that lncRNAs (lnc-NONMMUT064276.2, lnc-NONMMUT075728.1, and lnc-NONMMUT039653.2) may regulate pigmentation by regulating target genes. To reveal potential antisense lncRNA-mRNA interactions, we searched all lncRNA-mRNA duplexes using RNAplex, and found 97 lncRNAs interacted with mRNAs. The luciferase assay confirmed that TCONS_00049140 binded to Krt80 by the co-transfection of pVAX1-TCONS_00049140 and pGL0-Krt80 expression plasmids in 293T cell, based on the bioinformatics analysis. Overexpression of TCONS_00049140 in mouse melanocytes down-regulated Krt80 and resulted in the phenotype of increased cell proliferation and increased melanin production. The results suggested that TCONS_00049140 contributed to skin thickening through Krt80. Our findings provide a direction for research of the molecular mechanism of Cdk5 function.